1. Field of the Invention
The present invention relates to an encapsulated toner employable for producing a visible image from a latent image in an electrostatographic recording method and a process for forming a visible image employing the same.
2. Description of Prior Art
As the process for fixing a toner image in a recording method such as electrostatography, there have been known three fixing processes, that is, a heat fixing process, a solvent fixing process and a pressure fixing process. Recently, the heat fixing process and the pressure fixing process, both using no solvent, are widely used from the viewpoint of prevention of environmental pollution.
In the heat fixing process, a toner comprising a colorant dispersed in a binder has been conventionally employed. Such conventional toner has been also employed in the pressure fixing process. However, utilization of an encapsulated toner has recently proposed in the pressure fixing process.
The encapsulated toner is a toner in the form of micro-capsule prepared by enclosing a core material comprising a colorant such as carbon black and a binder with a resin shell which is rupturable by application of pressure.
The known encapsulated toner is not necessarily satisfactory in various properties essentially required for electrostatography.
As a material to be contained in the core material which is enclosed with a resin shell to form a microcapsule, an oily medium is widely used because of its high fixability. However, in the case of using the conventional oily material such as esters, aromatic substances and ether, the oily material contained in the capsule is liable to cause deterioration of a photosensitive material in the course of long-term running.
In the case of using an aliphatic oily material as the oily medium, the miscibility thereof with a component for forming a resin shell is low and hence thus prepared micro-capsule is not satisfactory in physical properties, though the aliphatic oily material less deteriorates the photosensitive material.